OASIS

OASIS (Open Artwork System Interchange Standard) is a newer packed file for the same kind of factory drawing as Graphic Design System II, built so huge designs do not waste a disk on repeated stamps.

A field of identical rectangles. A newer file can store the rectangle once and the step beside it.

People open an OASIS file when Graphic Design System II (GDSII) grows painful: flattened fill, large memories, and optical correction shapes. OASIS stores cell names, layer pairs, and geometry, then adds tighter packing, repetition, and optional compression. The meaning is still “here is geometry.” The win is size and read time. A .oas can be a few times smaller than the same design as .gds, and sometimes much smaller if array data and fill stay compact. A 20 gigabyte GDS dump might become a 4 gigabyte OASIS if the writer keeps hierarchy.

Mask shops and foundries publish which format they accept. Many accept both. Some rule decks still assume GDSII layer maps. Translate with care. A writer that explodes every repeat undoes the point of the packing. The everyday sibling is still GDSII. A stream in conversation can mean either file. Neither file is a PDK. Both need a layer map before anyone builds silicon. OASIS is not a smarter process format. It does not store devices or voltages. It stores shapes more politely, which is the whole of OASIS when GDS gets huge. The older file those shapes still travel in is GDSII in plain language. Either file is only a layout once a layer map says which sheet is which film.